For many years, research has linked educational achievement to life trajectories, such as occupational status, health or happiness.

But, the study explains that genes have substantial influence on academic success. The kids were highly stable throughout schooling, meaning that most students who started off well in primary school continued to do well until graduation.

“Around two-thirds of individual differences in school achievement are explained by differences in children’s DNA,” says Margherita Malanchini, a psychology postdoctoral fellow at the University of Texas at Austin.

“But less is known about how these factors contribute to an individual’s academic success overtime,” Malanchini adds.

“Our findings should provide additional motivation to identify children in need of interventions as early as possible, as the problems are likely to remain throughout the school years,” says Kaili Rimfeld, a postdoctoral researcher at the King’s College London.

For the study, the team analysed test scores from primary through the end of compulsory education of more than 6,000 pairs of twins.

Genetic factors explained about 70 per cent of this stability, while the twins shared environment contributed to about 25 per cent, and their non-shared environment, such as different friends or teachers, contributed to the remaining 5 per cent.

However, at times grades did change, such as a drop in grades between primary and secondary school. Those changes, researchers said, can be explained largely by non-shared environmental factors.

Toddlers like high-status winners

The results demonstrated how toddlers use social cues and prefer to affiliate themselves with the winners of conflicts and avoid those who they have seen yield to others.

“The way you behave in a conflict of interest reveals something about your social status,” says lead author Ashley Thomas from University of California, Irvine.

“Across all social animal species, those with a lower social status will yield to those above them in the hierarchy. We wanted to explore whether small children also judge high and low status individuals differently,” she adds.

For the study, published in the journal Nature Human Behavior, the team included a small group of toddlers aged 21 to 31 months, and presented them with two puppets that attempt to cross a stage in opposite directions.

When the puppets meet in the middle, they block each other’s way. One puppet then yields to the other and moves aside, allowing the other puppet to continue and reach its goal of crossing the stage.

Majority of the kids reached for the puppet that had won the conflict on the stage — the unyielding puppet, indicating that they preferred the high-status puppet — the one that others voluntarily yield to.

Further, the researchers explored whether toddlers would still prefer the winning puppet, if it won by using brute force.

The team exposed a new group of toddlers to the same puppet show, but this time, one puppet would forcefully knock the other puppet over to reach its goal. Majority of children avoided the winning puppet and reached for the victim instead.